This work presents the first edition and study of the grammatical compendium commonly attributed to Folchino dei Borfoni. Based on two main manuscripts, it is the first complete modern critical edition of a fourteenth-century Italo-Latin grammar. Originally intended for teaching Latin to native Italian speakers in Cremona during the last quarter of the fourteenth century, the compendium represents a prime example of medieval linguistic theory on the threshold of Italian Humanism. The text will interest not only students of the history of education, grammar, linguistics, and the Latin language, but also those interested in Romance languages and historical linguistics due to the many vernacular-Latin translations used to edify Folchino’s rules. DeSantis opens the volume with an extensive introduction in which she presents her findings on Folchino’s life, previous scholarship, Folchino’s other known works, and manuscript descriptions; she draws on codicological and textual evidence to prove the authenticity of Folchino as the author. The following chapters include a discussion of Folchino’s sources, an analysis of the methodology, terminology, content and structure of the text, and a study of the language, both Latin and vernacular, used in the text. An appendix provides a detailed linguistic description of the northern Italian dialect found throughout the grammar.